<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            margin: 0;
            background-color: #000;
        }
        .container {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
        }
        .dot {
            width: 50px;
            height: 50px;
            background-color: #fff;
            border-radius: 50%;
            float: left;
            margin: 16px;
        }

        .dot:nth-child(1) {
            animation: ani 1s linear infinite;
        }

        .dot:nth-child(2) {
            animation: ani 1s linear infinite .2s;
        }

        .dot:nth-child(3) {
            animation: ani 1s linear infinite .4s;
        }

        @keyframes ani {
            0% {
                transform: scale(.5);
            }
            50% {
                transform: scale(1.3);
            }
            100% {
                transform: scale(.5);
            }
        }

    </style>
</head>
<body>
    <div class="container">
        <div class="dot"></div>
        <div class="dot"></div>
        <div class="dot"></div>
    </div>
</body>
</html>